Rotary brush core assembly

ABSTRACT

A brush core for supporting and rotatably driving a brush or series of parallel brush rings carrying radially extending brush filaments includes a plurality of flat surfaces forming a polygon tangentially circumscribing a central supporting shaft coplanarly extended outwardly to the inner surface of the brush, the flat surfaces rotatably driven by means engaging an end flange.

United States Patent [191 Lewand Aug. 26, 1975 1 ROTARY BRUSH COREASSEMBLY [75] Inventor: Susan H. Lewand, Colonia, NJ.

[73] Assignee: Danline Manufacturing Company, Kenilworth, NJ.

22 Filed: Feb. 7, 1974 21 Appl. N01: 440,369

[52] US. Cl 15/181; 300/21 [51] Int. Cl A46b 7/10 [58] Field of Search15/179, 181, 182, 183,

[56] References Cited UNITED STATES PATENTS 3,321,799 5/1967 Hackworth15/182 3,471,889 10/1969 Mikke1sen..... 29/129 X 3,481,017 12/1969 Hunt29/123 3,839,763 10/l974 Gould 15/181 FOREIGN v PATENTS OR APPLICATIONS1,032,286 6/1966 United Kingdom 15/181 Primary Examiner-Peter FeldmanAttorney, Agent, or FirmLitt1epage, Quaintance, Murphy & Dobyns [5 7ABSTRACT A brush core for supporting and rotatably driving a brush orseries of parallel brush rings carrying radially extending brushfilaments includes a plurality of flat surfaces forming a polygontangentially circumscribing a central supporting shaft coplanarlyextended outwardly to the inner surface of the brush, the flat surfacesrotatably driven by means engaging an end flange.

6 Claims, 9 Drawing Figures PATENTEB AUG 2 6 I975 ROTARY BRUSH COREASSEMBLY BACKGROUND OF THE INVENTION 1. Field of the Invention NL N (A(tan 1r/N tan (arccos A/B) -T (cot 2rr/N cot (arccos A/B) and E (A T)sec rr/N T 1% sec ar/N -l). Generally, the considerations of strength ofmaterials This invention relates to rotary heads and casings of requiresthat B 5 5A.

brushes and brooms and more particularly to assemblies for supportingand driving a brush or series of brushes carrying radially extendingbristles.

2. Prior Art Circular tubes have been suggested as cores for radiallyextending brushes, but have been generally considered as too heavy. Anexample of such an apparatus is found in US. Pat. Nos. 2,757,401 and3,481,017.

A plurality of angle members fixed parallel to a rotation axis byradially extending cross-member plates has also been suggested as abrush core. Such a structure is not only expensive to produce andassemble, but is susceptible to misalignment during use. An example ofsuch an apparatus if found in US. Pat. No. 3,321,799.

Another previously known structure consists of a plurality of inwardlyopening U-shaped plates joined together by flat plates fixed to the topsof the Us, the tube formed thereby supported by end plates extendingfrom a central axis into the U openings. While some advantages are to berealized, the core is subject to unwanted flexing and bending duringoperation, possibly resulting in permanent misalignment. An example ofthis structure is to be found in US. Pat. No. 3,471,889.

Flat plates have also been joined in more simple polygonal tube shapeswith projecting plate flanges, the tubes supported again by end platesfixed to the polygon and to the central axis. Again, unwanted flexingand bending possibly resulting in permanent misalignment or metalfatigue contributing to structural failure can result. An example ofthis structure is to be found in British Pat. No. 1,032,286.

SUMMARY OF THE INVENTION A brush core which resists flexing and bendingwithout resorting to costly cross-member construction consists of aplurality of flat surfaces joined to form a regular polygon tangentiallycircumscribing a central supporting shaft. Each surface is geometricallyproduced or coplanarly extended at an apex of the polygon to the insidesurface of the brushes supported and rotatably driven by the brush core.End flanges fixed to the surfaces are rotatably driven by engagingmeans, typically pins, rotated by a motor means.

The preferred polygon is determined by minimizing the materialsnecessary to form the polygonal shape, thus reducing the weight as muchas possible, while retaining the basic structural features which preventunwanted displacement of the core. The parameters to be considered arethe radius of the central shaft, the inside radius of the brushes, andthe strength of the material under consideration.

In general if N is the number of sides of the regular polygon to bechosen, each side made of a plate having a thickness T much thinner thanthe radius A of the central shaft, and B is the inside radius of thebrush rings then the number of sides of the core is determinedapproximately by the following relations NL NA (tan vr/N tan (arccosA/B) and E A sec (Tr/N).

considering the variation due to the thickness of the flat plates, therelations become If the radii A and B are free to be chosen, thestrongest structure is presented by a core of triangular crosssectionand A and B should be appropriately chosen to satisfy the parameterswhen N 3.

Each of these relations will become apparent from the followingdiscussion of the Figures.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of arotary brush core assembly with the removable end flange removed.

FIG. 2 is an end view of the brush core of FIG. 1.

FIG. 3 is a perspective view of a brush ring usable with a brush coreaccording to this invention.

FIG. 4 is a geometric simplification of a square brush core.

FIG. 5 is a geometric simplification of a triangular brush core.

FIG. 6 is a diagrammatic representation of a portion of an N-sided brushcore.

FIG. 7 is a detail of a portion of FIG. 6 modified to some extent.

FIG. 8 is a detail of another portion of FIG. 6.

FIG. 9 is an end view of an extruded brush core according to thisinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows in perspective arotary brush core assembly 10 according to this invention which iscomposed of a plurality of flat rectangular metallic sheets 12. Thesheets are skip-welded or otherwise fixedly joined at the platejunctions 14. The junctions can be viewed as the apices of a regularpolygon, the sides of which are formed by the plates 12. Each plate 12extends coplanarly from the apex 14 to the inside of the brush rings.The plates are each tangent to a central shaft 16 which supports thecore and is easily slidably removable therefrom. The shaft may be eithersolid or tubular, depending on the strength of materials selected foruse as well as other parameters.

Welded or otherwise secured to one end of the polyg onal core 10 is afixed end flange 18 having a plurality of holes or other means 20 forengaging a motor-driven element (not shown) adapted'to rotate the brushcore. At the opposite end from the fixed end flange 18 is a removableend flange 22 removably secured to the core by bolts or screws 24. Theremovable end flange 22 can also have slots or holes 26 adapting the endflange to a number of drive means not shown.

An end view of the brush core assembly of FIG. 1 is shown in FIG. 2 withthe removable end flange 22 removed. The flat metal plates 12 are eachslidably tangent to the central shaft 16, the shaft being in general apart of a larger apparatus utilizing the brush core and not an integralpart of the brush core as such. Nuts 28 can be secured to the flatplates 12 to receive the bolts or screws 24 securing the removableflange 22 to the rest of the core assembly. The dotted line 30 indicatesthe position of the inside surface of the brush ring shown in FIG. 3. i

The brush ring 32 is of standard conventional design having a metallichub 34 crimped or otherwise securing the brush fiber material 36. Adrivepin 38 fixed to'the hub 34 is used to rotate the whole brush ring bycontacting the extended portionsof the brush core flat plates 12.- j i IThe use of flat plates which are readily. available and require nospecial forming or bending operations simplify and speed the fabricationof the brush:core. The resulting core is easierto use in that thetangencyof the plates 12 to the central shaft 16 ensures centeringof thecore on the shaft and eliminates the needfor manual alignment of thecore and end plates. The whole brush core with brush rings in placethereon can be slidably removed from the central supporting shaft oralternatively the core can be left in place and the brush rings changedby removing the end flange 22 and sliding the brush rings off the core.As well as minimizing the weight of the core by selectingthe optimumnumber; of flat plates consistent with the relations herein developed,the weight is additionally'reduced by eliminating the need for separateH brush-retaining end flanges and core supporting end 38 of the brushring to be contacted at the base of the pin next to theirlside surfaceof the brush ring, thereby minimizing the bending load applied to thepin. A brush core according to this invention can also be formed of aplastic resin or metal by conventional continuousextrusion methods. Sucha core 210 shown in FIG. 9 has a plurality of flat surfaces 212 whichform unitarily a regular polygon and coplanarly extend from fthe'apices214 of the polygon to the inside of a brush 230 rotatably carried by thecore. A drive pin or bar 238 fixed to the brush 230 is contacted at itsbase by one of the flat surfaces 212 to rotatably drive the brush 230.The extruded core 210 is supported by a central shaft 216 which may besolid or hollow. The flat surfaces 212 are tangent to theshaft 216, buteasily slidably. removable therefrom. Where tangenfand tangentially a'reiu sed in this specification and iri the claims, it is to include v notonly strong frictional e'ngagement between a curvedsurface and a flatplane, but

also the substantial physical equivalent considering the dimensionaltolerances which are necessary to permit easy removal and replacement ofthe elements concerned. Brush is used herein generically to include asingle element or a plurality of elements whether in cylindrieal, ring,spiral strip, or other form.

' 'The triangular cores shown in FIGS. 1, 2 and 9 have the preferredconfiguration as it represents the strongest of thepossiblepolygon-cross sections. If either the inside radius of the brush or theoutside radius of the central shaft are not subject to other conflictingconstraints, they should be chosen such that the other parameters hereindeveloped can be used with N 3.

" In FIGS. 4 and 5, a square 110 and a triangle 112 respectively arecircumscribed about a. circle. of radiu'sA. The square 110 and thetriangle 112 are each tangenttothe inscribed circle 114'at points 116.Each side of the regular polygons 1il0-and 112 are geometricallyproduced at an apex of the polygon to a concentric circle 118 of radiusB, each line segment so pro..

duced indicated by the numeral 12 If C is a radius vector to an apex 117of the polygon and A is a radius vector to an adjacent point on thepolygon tangent to the inscribed circle 114 then the angle between thetwo vectors is 'rr/3 in the case of the triangle, 'rr/4 in the case ofthe square or, in general, 'Ir/N in the case of a regular polygon havingN sides.

Toinsure that the polygon is in fact a closed figure, the radius B ofthe circle 118 must be greater than the length of the' vector C.

The length of half of a side-of the polygon (the length of the linesegment between the tips of the vectors A and C) is equal to A tan rr/N.The length of a side of a polygon is then 2A tan 'lT/N.

If B is a radius vector to a point of intersection on circle 118 with aproduced side 120 of the concentric polygon, and A is a radius vector tothe point of tangency on the same side of the polygon, then the angle 6between the two vectors is equal to arccos A/B and the length of theline segment opposite that angle is equal to A tan (arccos A/ B).

The total length L; of a side of a polygon and the line segment producedtherefrom to circle 1 18 is then given by L A tan rr/N A tan (arccosA/B). The total length of all such line segments forming the N sides ofthe polygon and the single segments 120 produced therefrom is NL NA (tan7T/N tan (arccos A/B) A rotary brush core assembly as shown in FIGS. 1-3can be constructed based upon the geometric relations herein developedwhere the circle 114 represents the central supporting shaft 16 andcircle 118 represents the inner surface 30 of rings, cylinders, orhelical closewound strips carrying radially extending bristles. Thesides of the regular polygon and the single segments extending therefromrepresent a plurality of. flat surfaces 12 circumscribing the supportingshaft 16. Since the weight of the flat surfaces 12 is largely dependentupon their dimensions and it is desirable to build as light weight acore as possible consistent with strength requirements, the quantity NLshould be minimized for any particular sizes of A and B by selecting apolygon of the proper number of sides N. For example, if B 3A then for atriangular core NL 13.7A

while for a square core NL 15.3A, and since the triangular core has thesmaller linear dimension, it would be selected.

If B is too small as compared to A, then a triangular core cannot beused as the triangle will not be completed inside the circle 118 andstill remain outside t e circle 114. The radius B must be greater than Cto retain the general configuration intended. C in general is equal to Asec Tr/N. If for example B 1.8A, for a triangular core NL 9.69A, for asquare core NL 10.0A, for a pentagonal core NL z 11.15A, and for ahexagonal core NL z 12.48A. While the triangular core would appear to bethe best selection, B A see 'rr/N or in this example see w/N 1.8 and ifN 3, sec *rr/N 2.00; if N 4, sec 'rr/N 1.42; if N 5, sec 1r/N 1.24; andif N 6, sec 1r/N 1.16. The core must then have 4 or more sides tosatisfy all the requirements present in this example.

7 lateral triangle which is congruent with any triangle formed byjoining an apex with the two closest points of tangency. The fourtriangles thus formed represent a superior configuration from thestandpoint of strength. In all such configurations, the central figureformed by joining the points of tangency is reflective of the polygoncircumscribing the circle 114.

FIG. 6 shows a portion of a brush core having N sides circumscribedabout circle 114 and produced out to a concentric circle 118representing similar portions of structure as in previous figures. Thelines of the polygon and segments produced therefrom in FIGS. 4 and 5have been replaced with elements 112 having a thickness T. Vectors A, B,and C are similarly situated as in FIGS. 4 and 5. Vector B is a radiusvector to the point of intersection between element 122 and circle 118.The angle between vectors A and C is 1r/N, while the angle 0 betweenvectors A and B is arccos A/B.

The thickness of element 122 changes the relations previouslydetermined. FIG. 7 is an enlargement of the section of FIG. 6 showingthe intersection of the two shown elements 122 modified by therequirement that the elements just meet. This condition specifies theminimum radius B for the outer circle 1 l8 and the minimum is shown asthe dotted extension of the vector C to the circle 118. That is, B C A"to retain the general structure intended.

As shown in the detail of FIG. 7, the length A'is the hypotenuse of aright triangle having one leg 124 of length T, the thickness of theelement 122. The leg 124 is parallel to vector A which, similarly tovector A, is at an angle 7T/N from vector C. The angle between leg 124and length A is then also vr/N and A =T sec IT/N.

The length A is a leg in yet another right triangle with the angleopposite that leg equal to 1r/N The hypotenuse 126 of the triangle has alength equal to the length of the hypotenuse 128 of the triangle having6 for a leg-minus leg 130 of the triangle having A as a hypotenuse. Theleg 130 has length T csc 'rr/N, while hypotenuse 128 has length T csc21r/N. I-Iypotenuse 126 must therefore have a length of T( csc 21r/N csc1r/N) and A T (csc 21r/N csc rr/N) sin vr/N. This may be simplified to AT /2 sec 'rr/N 1) and thus B (A T) sec 'rr/N T( /zsec1r/N 1).

FIG. 8 is an enlargement of that portion of FIG. 6 showing the element122 contacting the circle 118. At the circle 118 contacting end, eachelement 122 is shortened by a length 6 from the line segments 120 ofFIGS. 4 and 5. Since the angle between the line segment e, and thecircle 118 is equal to angle 6 of FIG. 6, e, z Tcot (arccos A/B). Theelement 122 is shortened on the other end by a length 6 shown in FIG. 7given by 6 T cot 21r/ N. Thus the length L of each element is L A(tan'n/N tan (arccos A/B)) T(cot 21r/N cot (arccos A/B)).

What is claimed is:

1. In a rotatably driven brush assembly comprising a central supportingshaft, a brush core slidably mounted on the supporting shaft, and abrush circumferentially encompassing the core and carrying radiallyextending brush filaments, an improved brush core comprising a pluralityof flat plates forming a regular polygon tangentially circumscribingsaid supporting shaft, each plate coplanarly extended at an apex of thepolygon to the inside surface of said brush.

2. The brush core of claim 1 further comprising end flanges fixed tosaid plurality of flat surfaces having a diameter greater than theinside diameter of the brush for retaining the brush on the core.

3. The brush core of claim 2 wherein at least one of said flanges isremovably fixed to the plurality of flat surfaces for allowingreplacement of the brush.

4. The brush core of claim 3 wherein at least one of said flangesfurther comprises means for receiving motive power and thereby rotatablydriving said brush.

5. In a rotatably driven brush assembly comprising a central supportingshaft, a brush core slidably mounted on the supporting shaft, a brushcore slidably mounted on the supporting shaft, and a brushcircumferentially encompassing the core and carrying radially extendingbrush filaments, an improved brush core comprising three flat platesforming a regular triangle tangentially circumscribing said supportingshaft, each plate coplanarly extended at an apex of the triangle to theinside surface of said brush, and two flanges, one fixed to eachopposite end of the three plates for retaining the brush on the core, atleast one of said flanges having engaging means for receiving motivepower, and at least one of said flanges being removably fixed to thejoined flat plates for allowing replacement of the brush.

6. In a rotatably driven brush assembly comprising a central supportingshaft of radius A, a brush core slidably mounted on the supportingshaft, and a brush having an inside radius of B circumferentiallyencompassing the core and carrying radially extending brush filaments,an improved brush core comprising a plurality of flat plates ofthickness T and of equal length L forming a regular polygon having Nsides tangentially circumscribing said supporting shaft, each platecoplanarly extended at an apex of the polygon to the inside surface ofsaid brush and the values of B, N, T, L and A determined by therelations B (A T)sec 'rr/B T /2 sec rr/N 1) and NL N (A (tan qr/N tan(arccos A/B)) T (cot 2'rr/N cot (arccos A/B))).

1. In a rotatably driven brush assembly comprising a central supportingshaft, a brush core slidably mounted on the supporting shaft, and abrush circumferentially encompassing the core and carrying radiallyextending brush filaments, an improved brush core comprising a pluralityof flat plates forming a regular polygon tangentially circumscribingsaid supporting shaft, each plate coplanarly extended at an apex of thepolygon to the inside surface of said brush.
 2. The brush core of claim1 further comprising end flanges fixed to said plurality of flatsurfaces having a diameter greater than the inside diameter of the brushfor retaining the brush on the core.
 3. The brush core of claim 2wherein at least one of said flanges is removably fixed to the pluralityof flat surfaces for allowing replacement of the brush.
 4. The brushcore of claim 3 wherein at least one of said flanges further comprisesmeans for receiving motive power and thereby rotatably driving saidbrush.
 5. In a rotatably driven brush assembly comprising a centralsupporting shaft, a brush core slidably mounted on the supporting shaft,a brush core slidably mounted on the supporting shaft, and a brushcircumferentially encompassing the core and carrying radially extendingbrush filaments, an improved brush core comprising three flat platesforming a regular triangle tangentially circumscribing said supportingshaft, each plate coplanarly extended at an apex of the triangle to theinside surface of said brush, and two flanges, one fixed to eachopposite end of the three plates for retaining the brush on the core, atleast one of said flanges having engaging means for receiving motivepower, and at least one of said flanges being removably fixed to thejoined flat plates for allowing replacement of the brush.
 6. In arotatably driven brush assembly comprising a central supporting shaft ofradius A, a brush core slidably mounted on the supporting shaft, and abrush having an inside radius of B circumferentially encompassing thecore aNd carrying radially extending brush filaments, an improved brushcore comprising a plurality of flat plates of thickness T and of equallength L forming a regular polygon having N sides tangentiallycircumscribing said supporting shaft, each plate coplanarly extended atan apex of the polygon to the inside surface of said brush and thevalues of B, N, T, L and A determined by the relations BN > (A + T)secpi /B + T ( 1/2 sec pi /N - 1) and NL N (A (tan pi /N + tan (arccosA/B)) - T (cot 2 pi /N + cot (arccos A/B))).